Selective Hydrogenation Catalyst and Methods of Making and Using Same

ABSTRACT

A composition comprising an extruded inorganic support comprising an oxide of a metal or metalloid, and at least one catalytically active metal, wherein the extruded inorganic support has pores, a total pore volume, and a pore size distribution, wherein the pore size distribution displays at least two peaks of pore diameters, each peak having a maximum, wherein a first peak has a first maximum of pore diameters of equal to or greater than about 120 nm and a second peak has a second maximum of pore diameters of less than about 120 nm, and wherein greater than or equal to about 5% of a total pore volume of the extruded inorganic support is contained within the first peak of pore diameters.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 14/799,440 filed on Jul. 14, 2015, published asUS2015/0314270 which is a continuation of U.S. patent application Ser.No. 14/224,887 filed Mar. 25, 2014, now U.S. Pat. No. 9,144,787, whichis a continuation of U.S. patent application Ser. No. 13/414,544 filedMar. 7, 2012, now U.S. Pat. No. 9,108,188, each of which is entitled“Selective Hydrogenation Catalyst and Methods of Making and Using Same,”and each of which is incorporated herein by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not applicable.

BACKGROUND

Technical Field

The present disclosure relates to the production of unsaturatedhydrocarbons, and more particularly to a selective hydrogenationcatalyst and methods of making and using same.

Background

Unsaturated hydrocarbons such as ethylene and propylene are oftenemployed as feedstocks in preparing value added chemicals and polymers.Unsaturated hydrocarbons can be produced by pyrolysis or steam crackingof hydrocarbons including hydrocarbons derived from coal, hydrocarbonsderived from synthetic crude, naphthas, refinery gases, ethane, propane,butane, and the like. Unsaturated hydrocarbons produced in these mannersusually contain small proportions of highly unsaturated hydrocarbonssuch as acetylenes and diolefins that can adversely affect theproduction of subsequent chemicals and polymers. Thus, to form anunsaturated hydrocarbon product such as a polymer grade monoolefin, theamount of acetylenes and diolefins in the monoolefin stream is typicallyreduced. For example, in polymer grade ethylene, the acetylene contenttypically is less than about 2 ppm.

One technique commonly used to reduce the amount of acetylenes anddiolefins in an unsaturated hydrocarbon stream primarily comprisingmonoolefins involves selectively hydrogenating the acetylenes anddiolefins to monoolefins. This process is selective in thathydrogenation of the monoolefin and the highly unsaturated hydrocarbonsto saturated hydrocarbons is minimized. For example, the hydrogenationof ethylene or acetylene to ethane is minimized. An ongoing need existsfor improved selective hydrogenation catalysts.

SUMMARY

Disclosed herein is a composition comprising an extruded inorganicsupport comprising an oxide of a metal or metalloid, and at least onecatalytically active metal, wherein the extruded inorganic support haspores, a total pore volume, and a pore size distribution, wherein thepore size distribution displays at least two peaks of pore diameters,each peak having a maximum, wherein a first peak has a first maximum ofpore diameters of equal to or greater than about 120 nm and a secondpeak has a second maximum of pore diameters of less than about 120 nm,and wherein greater than or equal to about 5% of a total pore volume ofthe extruded inorganic support is contained within the first peak ofpore diameters.

Also disclosed herein is a method of preparing a hydrogenation catalystcomprising extruding a mixture comprising an oxide of a metal ormetalloid, a pore former, and water to form an extrudate, drying theextrudate to form a dried extrudate, calcining the dried extrudate tofrom a calcined extrudate, contacting the calcined extrudate with achlorine-containing compound to form a chlorided support, reducing theamount of chloride in the chlorided support to form a cleaned chloridedsupport, and contacting the cleaned chlorided support with a Group 10metal and a Group 1B metal to form a hydrogenation catalyst, wherein apore size distribution for the hydrogenation catalyst displays at leasttwo peaks of pore diameters, each peak having a maximum, and wherein afirst peak has a first maximum of pore diameters that is equal to orgreater than about 120 nm and a second peak has a second maximum of porediameters that is less than about 120 nm.

Further disclosed herein is an extruded inorganic support comprising anoxide of a metal or metalloid, wherein the extruded inorganic supportdisplays a pore size distribution for at least two peaks of porediameters, each peak having a maximum, wherein a first peak has a firstmaximum of pore diameters of equal to or greater than about 120 nm and asecond peak has a second maximum of pore diameters of less than about120 nm, wherein greater than or equal to 15% of a total pore volume ofthe extruded inorganic support is contained within the first peak ofpore diameters, and wherein the inorganic support has a surface area offrom about 5 m²/g to about 15 m²/g.

Further disclosed herein is a method of preparing a hydrogenationcatalyst comprising selecting an inorganic support having a multimodaldistribution of pore diameters, wherein at least one distribution ofpore diameters comprises pores having a diameter of equal to or greaterthan about 120 nm, extruding a mixture comprising the inorganic supportand water to form an extrudate, drying the extrudate to form a driedextrudate, calcining the dried extrudate to from a calcined extrudate,and contacting the calcined extrudate with a Group VIII metal and aGroup 1B metal to form a hydrogenation catalyst.

Further disclosed herein is a method comprising preparing a plurality ofextruded inorganic supports consisting essentially of silica, titania,alumina, or a spinel, plotting the pore diameter as a function of a logof differential mercury intrusion for the extruded inorganic support,and identifying the extruded inorganic supports having at least twopeaks, each peak having a maximum, wherein a first peak comprises poreswith a first pore diameter maximum equal to or greater than about 120nm, and wherein the first peak of pore diameters represents greater thanor equal to about 5% of a total pore volume of the extruded inorganicsupport.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and theadvantages thereof, reference is now made to the following briefdescription, taken in connection with the accompanying drawings anddetailed description, wherein like reference numerals represent likeparts.

FIG. 1 depicts a process flow diagram of an embodiment of a selectivehydrogenation process.

FIGS. 2-6 are plots of the log of differential mercury intrusion as afunction of pore size diameter for the samples from Example 1.

FIG. 7 is a plot of the temperature necessary to maintain a 90%conversion of acetylene as a function of time for the samples fromExample 1.

FIG. 8 is a plot of the ethylene selectivity as a function of time forthe samples from Example 1.

DETAILED DESCRIPTION

It should be understood at the outset that although an illustrativeimplementation of one or more embodiments are provided below, thedisclosed systems and/or methods can be implemented using any number oftechniques, whether currently known or in existence. The disclosureshould in no way be limited to the illustrative implementations,drawings, and techniques illustrated below, including the exemplarydesigns and implementations illustrated and described herein, but can bemodified within the scope of the appended claims along with their fullscope of equivalents.

Disclosed herein are hydrogenation catalysts comprising a Group 10 metaland a catalyst support. In an embodiment the catalyst support comprisesan oxide of a metal or metalloid and displays a characteristic pore sizedistribution. Catalysts of the type disclosed herein can display ahydrogenation selectivity that remains stable over a longer time periodas will be described in more detail later herein.

In an embodiment, the catalyst comprises a support of an oxide of ametal or metalloid. In an embodiment, the catalyst support comprisessilica, titania, alumina, aluminate, or combinations thereof.Alternatively, the catalyst support consists or consists essentially ofsilica, titania, alumina, aluminate, or combinations thereof. In anembodiment, the catalyst support comprises a spinel. Alternatively, thecatalyst support consists or consists essentially of a spinel. Herein, aspinel refers to any of a class of minerals of general formulation A²⁺B₂³⁺O₄ ²⁻ which crystallize in the cubic (isometric) crystal system, withthe oxide anions arranged in a cubic, close-packed lattice and thecations A and B occupying some or all of the octahedral and tetrahedralsites in the lattice. Nonlimiting examples of materials suitable for usein the catalyst supports of this disclosure include aluminas, silicas,titanias, zirconias, aluminosilicates (e.g., clays, ceramics, and/orzeolites), spinels (e.g., zinc aluminate, zinc titanate, and/ormagnesium aluminate), or combinations thereof.

In an embodiment, the catalyst support comprises an alumina.Alternatively the catalyst support consists or consists essentially ofan alumina. For example, the catalyst support can comprise, consist of,or consist essentially of an alpha (α)-alumina support. The α-aluminasupport can be prepared using any suitable methodology. The aluminasupport can include additional components that do not adversely affectthe catalyst such as zirconia, silica, thoria, magnesia, fluoride,sulfate, phosphate, or mixtures thereof.

The catalyst support can have a surface area of from about 1 squaremeters per gram (m²/g), to about 35 m²/g, or alternatively of from about3 m²/g to about 25 m²/g, or alternatively of from about 5 m²/g to about15 m²/g. The surface area of the support can be determined using anysuitable method. An example of a suitable method for determining thesurface area of the support includes the Brunauer, Emmett, and Teller(“BET”) method, which measures the quantity of nitrogen adsorbed on thesupport.

In an embodiment, a catalyst support of the type disclosed herein isfurther characterized by a total pore volume as measured by differentialmercury intrusion in the range of from about 0.1 cc/g to about 0.6 cc/g,alternatively from about 0.2 cc/g to about 0.55 cc/g. The pore volume ofthe support can be measured by a differential mercury intrusion methodsuch as is described in ASTM UOP578-02, entitled “Automated Pore Volumeand Pore Size Distribution of Porous Substances by Mercury Porosimetry,”which is incorporated herein by reference in its entirety.

In an embodiment the catalyst support, the resultant catalyst, or bothof the type disclosed herein displays a plot of the pore diameter on alogarithmic axis as a function of a log of differential mercuryintrusion having two to four peaks corresponding to the presence of atleast two to four distributions of pore diameters. Hereinafter, a plotof the pore diameter on a logarithmic axis as a function of a log ofdifferential mercury intrusion is referred to as the pore sizedistribution.

In an embodiment, a catalyst support, the resultant catalyst, or both ofthe type disclosed herein is further characterized by an at leastbimodal pore size distribution. In an embodiment a catalyst support, theresultant catalyst, or both of the type disclosed herein displays a poresize distribution having at least two peaks corresponding to thepresence of at least two distributions of pore diameters. The firstpeak, designated peak A, corresponds to distribution A and can have afirst maximum of pore diameters equal to or greater than about 120 nm.For example, peak A can have a maximum of pore diameters of from about200 nm to about 9000 nm, alternatively from about 400 nm to about 8000nm, or alternatively from about 600 to about 6000.

The second peak, designated peak B, corresponds to distribution B andcan have a second maximum of pore diameters of less than about 120 nm.For example, peak B can have a maximum of pore diameters of from about15 nm to less than about 120 nm, alternatively from about 115 nm toabout 25 nm, or alternatively from about 115 nm to about 30 nm. Examplesof peak A and peak B are identified in FIGS. 3-6.

In an embodiment, the distance between the maximum of peak A and themaximum of peak B is at least about 400 nm, alternatively at least 500nm, alternatively from about 400 nm to about 3900 nm, or alternativelyfrom about 400 nm to about 2900 nm. In an embodiment peak A, peak B, orboth is non-Gaussian. In an embodiment, peak A is non-Gaussian anddisplays a peak width at half height that is greater than the peak widthat half height of peak B.

In an embodiment greater than or equal to about 5% of the total porevolume of the catalyst support, the resultant catalyst, or both iscontained within peak A, alternatively greater than or equal to about10% of the total pore volume of the catalyst support is contained withinpeak A, or alternatively greater than or equal to about 15% of the totalpore volume of the catalyst support is contained within peak A. In anembodiment from about 5% to about 75% of the total pore volume of thecatalyst support, the resultant catalyst, or both is contained withinpeak A, alternatively from about 10% to about 60% of the total porevolume of the catalyst support is contained within peak A, oralternatively from about 15% to about 40% of the total pore volume ofthe catalyst support is contained within peak A. In an embodiment lessthan or equal to about 95% of the total pore volume of the catalystsupport, the resultant catalyst, or both is contained within peak B,alternatively less than or equal to about 90%, alternatively less thanor equal to about 85%. In an embodiment from about 95% to about 25% ofthe total pore volume of the catalyst support, the resultant catalyst,or both is contained within peak B, alternatively from about 90% toabout 40% of the total pore volume of the catalyst support is containedwithin peak B, or alternatively from about 85% to about 60% of the totalpore volume of the catalyst support is contained within peak B.

In an embodiment, a catalyst support of the type disclosed herein isformed from a mixture comprising an oxide of a metal or metalloid, apore former, and water which are contacted to form an extrudate. Themixture can also include a pore former (also known as a pore generator)which can be any compound that can be mixed with the above componentsand that is combustible upon heating thereby producing voids. This poregenerator helps to maintain and/or increase the porosity of the catalystsupport composition. Examples of such pore generators include, but arenot limited to, cellulose, cellulose gel, microcrystalline cellulose,methyl cellulose, zinc stearate, flours, starches, modified starches,graphite, polymers, carbonates, bicarbonates, microcrystalline wax, ormixtures thereof. The amount of the pore generator component used inthis disclosure is in the range of about 0.1 to about 25 weight percent(wt. %) based on the total weight of the components (1.1-1.5).Alternatively, the amount ranges from about 1 wt. % to about 10 wt. %alternatively from about 3 wt. % to about 6 wt. %. Variation in rawmaterials, such as particle size and particle morphology of the aluminaused, can impact porosity and pore size distribution.

In an embodiment, the mixture can be formed into any suitable shape.Methods for shaping particles include, for example, extrusion, spraydrying, pelletizing, agglomerization, oil drop, and the like. In anembodiment, the mixture is formed into an extrudate, for example asdescribed in U.S. Pat. Nos. 5,558,851 and 5,514,362, each of which areincorporated herein in their entirety. In an embodiment, the mixturefurther comprises an extrusion aid. An extrusion aid can function toimprove the rheology of the mixture. This improvement in the rheology ofthe mixture can function to improve flow of the mixture through theextrusion die. Improved flow through the extrusion die can lead toeasier equipment start-up, smoother extrusion, faster processing, lowerextrusion pressures, and improved product appearance. Extrusion aids,their effective amounts and methods of incorporation into the mixturecan be varied and selected according to ordinary skill in the art.Hereafter, the shaped mixture exiting a die, with any composition or anyform, will be referred to as the “green extrudate.”

Excess water from the green extrudate can be removed by drying to form adried green extrudate prior to further processing. Conventional methodsfor drying wet solids can be used to dry the green extrudate, and caninclude, for example drying in air or an inert gas such as nitrogen orhelium. The air or inert gas can be circulating, moving, or static.Drying temperatures can range from about 200° F. to about 400° F.,alternatively from about 200° F. to about 300° F., alternatively fromabout 225° F. to about 275° F. Drying times can range from equal to orgreater than about 1 hour, alternatively from about 1 hour to about 10hours, alternatively from about 2 hours to about 5 hours.

In an embodiment, the dried green extrudate can be calcined to form acalcined extruded catalyst support. Calcination temperatures can rangefrom about 500° F. to about 1500° F., alternatively from about 700° F.to about 1400° F., alternatively from about 850° F. to about 1300° F.Calcination times can range from about 0.5 to about 12 hours,alternatively from about 1 to about 6 hours. In such embodiments, thecalcination can be carried out in an oxygen containing atmosphere. Asused herein, “dry” air refers to air having a dew point of less thanabout −40° F. The calcined extruded catalyst support can be directlyused in a catalyst preparation or can be further processed according tothe following description.

In an embodiment, a method of preparing a selective hydrogenationcatalyst comprises contacting a calcined extruded catalyst support ofthe type disclosed herein with a chlorine-containing compound. Thechlorine-containing compound can be a gas, a liquid, or combinationsthereof. An embodiment comprises contacting the catalyst support with aliquid chlorine-containing compound to create a chlorided catalystsupport. Such a liquid can comprise at least one chlorine-containingcompound. In some embodiments, the liquid chlorine-containing compoundto which the inorganic catalyst support can be exposed to create thechlorided catalyst support include, but are not limited to, hydrochloricacid; alkaline metal chloride; alkaline earth chloride;chlorohydrocarbons; compounds described by the formulaN(H_(v)R_(w)R′_(x)R″_(y)R′″_(z))Cl, where R, R′, R″, and R′″ is methyl,ethyl, propyl, butyl, or any combination thereof and v, w, x, y, z canbe 0 to 4 provided v+w+x+y+z=4; or combinations thereof. In someembodiments, the alkaline metal chloride can comprise potassiumchloride, sodium chloride, lithium chloride, or combinations thereof. Insome embodiments, the alkaline earth chloride can comprise calciumchloride, barium chloride, or combinations thereof. In some embodiments,compounds described by the formula N(H_(v)R_(w)R′_(x)R″_(y)R′″_(z))Clcan comprise ammonium chloride, methyl ammonium chloride,tetramethylammonium chloride, tetraethylammonium chloride, orcombinations thereof. Chloro-hydrocarbons as used herein can comprisecompounds containing 1-10 carbons wherein there is at least onesubstitution of hydrogen for chlorine. In some embodimentschloro-hydrocarbons comprise compounds described by the formulaCCl_(x)H_(y) (where x+y=4); compounds described by the formulaC₂Cl_(x)H_(y) (where x+y=6); or combinations thereof. In someembodiments compounds described by the formula CCl_(x)H_(y) comprisecarbon tetrachloride, dichloromethane, or combinations thereof. In someembodiments, compounds described by the formula C₂Cl_(x)H_(y) comprisetrichloroethane. In an embodiment, the liquid chlorine-containingcompound comprises potassium chloride in solution.

The calcined extruded catalyst support can be contacted with the liquidchlorine-containing compound in any suitable manner. In an embodiment,the method used to contact a calcined extruded catalyst support with aliquid chlorine-containing compound can be incipient wetnessimpregnation. During incipient wetness impregnation, the pores of thesupport become substantially filled with the liquid chlorine-containingcompound. Other contacting methods such as soaking can also be employedto contact the calcined extruded catalyst support with the liquidchlorine-containing compound to create a chlorided catalyst support.

An alternative embodiment comprises initially contacting the calcinedextruded catalyst support with a gaseous chlorine-containing compound tocreate a chlorided catalyst support. In some embodiments, thechlorine-containing compounds that can be employed as gases include, butare not limited to, hydrogen chloride gas, chlorine gas, CCl_(x)H_(y)(where x+y=4), C₂Cl_(x)H_(y) (where x+y=6), or combinations thereof. Inanother embodiment, the gaseous chlorine-containing compounds areobtained by heating a volatile chloro-hydrocarbon or mixture thereof.

A method used to contact a calcined extruded catalyst support with agaseous chlorine-containing compound can be accomplished by heating thecalcined extruded catalyst support in the presence of a gaseouschlorine-containing compound and optionally in the presence of oxygen,water, nitrogen, hydrogen or mixtures thereof to create a chloridedcatalyst support. In an embodiment, the calcined extruded catalystsupport can be contacted with a gaseous chlorine-containing compound attemperatures of from about 300° C. to about 850° C. for from about 0.2to about 20 hours.

The amount of chlorine-containing compound deposited on the calcinedextruded catalyst support is controlled independently of the contactmethod, whether by liquid contacting, gas phase contacting, orcombination thereof. The contacting method can deposit an amount ofchlorine-containing compound such that the chlorided catalyst support,i.e., the calcined extruded catalyst support after exposure to achlorine-containing compound, comprises from about 20 wt. % to about0.001 wt. % chlorine based on a total weight of the chlorided catalystsupport, alternatively from about 10 wt. % to about 0.01 wt. % chlorine,alternatively from about 2 wt. % to about 0.05 wt. % chlorine.

After the calcined extruded catalyst support has been contacted with thechlorine-containing compound to create the chlorided catalyst support,the chlorided catalyst support can be removed from contact with thechlorine-containing compound and processed to remove from the chloridedcatalyst support unwanted elements such as an amount ofchlorine-containing compound, decomposition products thereof, or otherunwanted elements to create a clean chlorided catalyst support andotherwise prepare the chlorided catalyst support for further processingto produce a selective hydrogenation catalyst. Removing an amount ofchlorine-containing compound and/or any other unwanted elements canoccur via a wash, via vaporization, or combinations thereof, depending,for example, on the type of chlorine-containing compound involved. Thevaporization can be accomplished at a temperature of from about 300° C.to about 850° C. for from about 0.2 to about 20 hours. After processing,the clean chlorided catalyst support can comprise from about 0 to about2000 ppm by weight of chlorine; alternatively, can comprise from about 1to about 1200 ppm by weight of chlorine; alternatively, from about 2 toabout 80 ppm by weight of chlorine; alternatively, from about 3 to about20 ppm, alternatively less than about 2 ppm by weight of chlorine withrespect to the support.

In an embodiment, a chlorided catalyst support produced by contact witha liquid chlorine-containing compound can be exposed to an elevatedtemperature of from about 50° C. to about 850° C. for from about 0.5 toabout 20 hours to dry and/or calcine the chlorided catalyst support,thereby producing a cleaned chlorided catalyst support. In someembodiments, an optional washing step can follow the exposure to anelevated temperature. For example, the support can be washed with waterat temperatures of from about 20° C. to about 100° C. for from about 1minute to about 2 hours. In an embodiment, the washing utilizes hotdistilled or deionized water and occurs after drying and/or calcining.Following the washing step, the chlorided catalyst support canoptionally undergo another exposure to an elevated temperature of fromabout 50° C. to about 900° C. for from about 0.5 to about 20 hours toremove any unwanted moisture.

In another embodiment, a chlorided catalyst support produced by contactwith a gaseous chlorine-containing compound can be cleaned viavaporization or washing or a combination thereof to remove an amount ofchlorine-containing compound, decomposition products thereof, or otherunwanted elements. In an embodiment, after contacting the catalystsupport with the gaseous chlorine-containing compound, flow of thegaseous chlorine-containing compound is stopped, and the gaseous treatedchlorided catalyst support can be continued to be heated and/or calcinedby exposure to an elevated temperature in the absence of the gaseouschlorine-containing compound to produce a cleaned chlorided catalystsupport. Exposure to an elevated temperature can occur in the presenceof oxygen, water, nitrogen and mixtures thereof for less than or equalto about 18 hours. This vaporization removal step can be optionallyfollowed by exposing the chlorided catalyst support with a heated streamof gas free of the chlorine-containing compound to further remove anyunwanted elements. After processing, the cleaned chlorided catalystsupport can comprise from about 0 to about 2000 ppm by weight ofchlorine; alternatively, can comprise from about 1 to about 1200 ppm byweight of chlorine; alternatively, from about 2 to about 80 ppm byweight of chlorine; alternatively, from about 3 to about 20 ppm,alternatively less than about 2 ppm by weight of chlorine with respectto the support.

In an embodiment, a method of preparing a hydrogenation catalystcomprises selecting an inorganic support having a multimodaldistribution of pore diameters. In an embodiment, at least onedistribution of pore diameters comprises pores having a diameter ofequal to or greater than about 120 nm. The selected support can then betreated as a catalyst support of the type disclosed herein and subjectedto the processing disclosed herein (e.g., drying, calcining,chloriding).

In an embodiment, a method of preparing a selective hydrogenationcatalyst comprises contacting a cleaned chlorided catalyst support ofthe type disclosed herein with at least one catalytically active metal,alternatively palladium. The palladium can be added to the cleanedchlorided catalyst support by contacting the cleaned chlorided catalystsupport with a palladium-containing compound to form a palladiumsupported composition as will be described in more detail later herein.Examples of suitable palladium-containing compounds include withoutlimitation palladium chloride, palladium nitrate, ammoniumhexachloropalladate, ammonium tetrachlopalladate, palladium acetate,palladium bromide, palladium iodide, tetraamminepalladium nitrate, orcombinations thereof. In an embodiment, the palladium-containingcompound is a component of an aqueous solution. An example ofpalladium-containing solution suitable for use in this disclosureincludes without limitation a solution comprising palladium metal.

In an embodiment, palladium is present in the mixture for preparation ofa selective hydrogenation catalyst in an amount of from about 0.005 wt.% to about 2 wt. %, alternatively from about 0.005 wt. % to about 1 wt.% or alternatively from about 0.005 wt. % to about 0.5 wt. % based onthe total catalyst weight.

In an embodiment, a method of preparing a selective hydrogenationcatalyst can initiate with the contacting of cleaned chlorided catalystsupport with a palladium-containing compound to form a supportedpalladium composition. The contacting can be carried out using anysuitable technique. For example, the cleaned chlorided catalyst supportcan be contacted with the palladium-containing compound by soaking, orincipient wetness impregnation of the support with apalladium-containing solution. In such embodiments, the resultingsupported palladium composition can have greater than about 90 wt. %,alternatively from about 92 wt. % to about 98 wt. %, alternatively fromabout 94 wt. % to about 96 wt. % of the palladium concentrated near theperiphery of the palladium supported composition, as to form a palladiumskin. In an embodiment, the cleaned chloride catalyst support iscontacted with the palladium-containing solution by soaking the supportin the palladium-containing solution.

The palladium skin can be any thickness as long as such thickness canpromote the hydrogenation processes disclosed herein. Generally, thethickness of the palladium skin can be in the range of from about 1micron to about 3000 microns, alternatively from about 5 microns toabout 2000 microns, alternatively from about 10 microns to about 1000microns, alternatively from about 50 microns to about 500 microns.Examples of such methods are further described in more details in U.S.Pat. Nos. 4,404,124 and 4,484,015, each of which is incorporated byreference herein in its entirety.

Any suitable method can be used for determining the concentration of thepalladium in the skin of the palladium supported composition and/or thethickness of the skin. For example, one method involves breaking open arepresentative sample of the palladium supported composition particlesand treating the palladium supported composition particles with a dilutealcoholic solution of N,N-dimethyl-para-nitrosoaniline. The treatingsolution reacts with the palladium to give a red color that can be usedto evaluate the distribution of the palladium. Yet another technique formeasuring the concentration of the palladium in the skin of thepalladium supported composition involves breaking open a representativesample of catalyst particles, followed by treating the particles with areducing agent such as hydrogen to change the color of the skin andthereby evaluate the distribution of the palladium. Alternatively, thepalladium skin thickness can be determined using electron probemicroanalysis.

The supported palladium composition formed by contacting the cleanedchlorided catalyst support with the palladium-containing solutionoptionally can be dried at a temperature of from about 15° C. to about150° C., alternatively from about 30° C. to about 100° C., alternativelyfrom about 60° C. to about 100° C.; and for a period of from about 0.1hour to about 100 hours, alternatively from about 0.5 hour to about 20hours, alternatively from about 1 hour to about 10 hours. Alternatively,the palladium supported composition can be calcined. This calcining stepcan be carried out at temperatures up to about 850° C., alternatively offrom about 150° C. to about 800° C., alternatively from about 150° C. toabout 750° C., alternatively from about 150° C. to about 700° C.; andfor a period of from about 0.2 hour to about 20 hours, alternativelyfrom about 0.5 hour to about 20 hours, alternatively from about 1 hourto about 10 hours.

In an embodiment, the selective hydrogenation catalyst can furthercomprise one or more selectivity enhancers. Suitable selectivityenhancers include, but are not limited to, Group 1B metals, Group 1Bmetal compounds, silver compounds, fluorine, fluoride compounds, sulfur,sulfur compounds, alkali metals, alkali metal compounds, alkalinemetals, alkaline metal compounds, iodine, iodide compounds, orcombinations thereof. In an embodiment, the selective hydrogenationcatalyst comprises one or more selectivity enhancers which can bepresent in total in the mixture for preparation of the selectivehydrogenation catalyst in an amount of from about 0.001 wt. % to about10 wt. % based on the total weight of the selective hydrogenationcatalyst, alternatively from about 0.01 wt. % to about 5 wt. %,alternatively from about 0.01 wt. % to about 2 wt. %. The amount ofselectivity enhancer incorporated into the selective hydrogenationcatalyst can be in the range described herein for the amount ofselectivity enhancer used to prepare the selective hydrogenationcatalyst.

In an embodiment, the selectivity enhancer comprises silver (Ag), silvercompounds, or combinations thereof. Examples of suitable silvercompounds include without limitation silver nitrate, silver acetate,silver bromide, silver chloride, silver iodide, silver fluoride, orcombinations thereof. In an embodiment, the selectivity enhancercomprises silver nitrate. The selective hydrogenation catalyst can beprepared using silver nitrate in an amount of from about 0.005 wt. % toabout 5 wt. % silver based on the total weight of the selectivehydrogenation catalyst, alternatively from about 0.01 wt. % to about 1wt. % silver, alternatively from about 0.05 wt. % to about 0.5 wt. %.The amount of silver incorporated into the selective hydrogenationcatalyst can be in the range described herein for the amount of silvernitrate used to prepare the selective hydrogenation catalyst.

In an embodiment, the selectivity enhancer comprises alkali metals,alkali metal compounds, or combinations thereof. Examples of suitablealkali metal compounds include without limitation elemental alkalimetal, alkali metal halides (e.g., alkali metal fluoride, alkali metalchloride, alkali metal bromide, alkali metal iodide), alkali metaloxides, alkali metal carbonate, alkali metal sulfate, alkali metalphosphate, alkali metal borate, or combinations thereof. In anembodiment, the selectivity enhancer comprises potassium fluoride (KF).In another embodiment, the selective hydrogenation catalyst is preparedusing an alkali metal compound in an amount of from about 0.01 wt. % toabout 5 wt. % based on the total weight of the selective hydrogenationcatalyst, alternatively from about 0.03 wt. % to about 2 wt. %,alternatively from about 0.05 wt. % to about 1 wt. %. The amount ofalkali metal incorporated into the selective hydrogenation catalyst canbe in the range described herein for the amount of alkali metal compoundused to prepare the selective hydrogenation catalyst.

In some embodiments, one or more selectivity enhancers of the typedescribed previously herein can be added to the supported palladiumcomposition. In an embodiment, silver can be added to the supportedpalladium composition. For example, the supported palladium compositioncan be placed in an aqueous silver nitrate solution of a quantitygreater than that necessary to fill the pore volume of the composition.The resulting material is a palladium/silver supported composition(herein this particular embodiment of the selective hydrogenationcatalyst is referred to as a Pd/Ag composition). The Pd/Ag compositionmay be dried and/or calcined as previously described herein.

In an embodiment, one or more alkali metals can be added to the Pd/Agcomposition using any suitable technique such as those describedpreviously herein. In an embodiment, the selectivity enhancer comprisespotassium fluoride, and the resulting material is apalladium/silver/alkali metal fluoride supported composition (hereinthis particular embodiment of the selective hydrogenation catalyst isreferred to as a Pd/Ag/KF composition).

In an embodiment, the supported palladium composition is contacted withboth an alkali metal halide and a silver compound. Contacting thesupported palladium composition with both an alkali metal halide and asilver compound can be carried out simultaneously; alternatively thecontacting can be carried out sequentially in any user-desired order.

In an embodiment, a selective hydrogenation catalyst formed inaccordance with the methods disclosed herein comprises an α-aluminasupport of the type disclosed herein, palladium, and one or moreselectivity enhancers, (e.g., silver and/or potassium fluoride). Theselective hydrogenation catalyst (Pd/Ag, Pd/KF, and/or thePd/Ag/KF/compositions) can be dried to form a dried selectivehydrogenation catalyst. In some embodiments, this drying step can becarried out at a temperature in the range of from about 0° C. to about150° C., alternatively from about 30° C. to about 100° C., alternativelyfrom about 50° C. to about 80° C.; and for a period of from about 0.1hour to about 100 hours, alternatively from about 0.5 hour to about 20hours, alternatively from about 1 hour to about 10 hours.

The dried selective hydrogenation catalyst can be reduced using hydrogengas or a hydrogen gas containing feed, e.g., the feed stream of theselective hydrogenation process, thereby providing for optimum operationof the selective hydrogenation process. Such a gaseous hydrogenreduction can be carried out at a temperature in the range of from, forexample, about 0° C. to about 400° C., alternatively 20° C. to about300° C., or alternatively about 30° C. to about 250° C.

In an embodiment, a selective hydrogenation catalyst of the typedisclosed herein can catalyze a selective hydrogenation process. In someembodiments a selective hydrogenation catalyst of the type disclosedherein is used in conjunction with one or more conventionalhydrogenation catalysts to catalyze a selective hydrogenation process.In such embodiments having a conventional hydrogenation catalyst and aselective hydrogenation catalyst of the type disclosed herein, theselective hydrogenation catalyst may be present in an amount thatcomprises greater than about 50% of the total amount of hydrogenationcatalyst present during the selective hydrogenation process.Alternatively greater than about 70% or alternatively greater than about85%. Herein, the phrase “conventional hydrogenation catalysts” refers tohydrogenation catalysts that lack a catalyst support of the typedisclosed herein.

The selective hydrogenation catalyst can be contacted with anunsaturated hydrocarbon stream primarily containing unsaturatedhydrocarbons, e.g., ethylene, but also containing a highly unsaturatedhydrocarbon, e.g., acetylene. The contacting can be executed in thepresence of hydrogen at conditions effective to selectively hydrogenatethe highly unsaturated hydrocarbon to an unsaturated hydrocarbon. In anembodiment, the selective hydrogenation catalysts of the type disclosedherein are used in the hydrogenation of highly unsaturated hydrocarbonssuch as for example and without limitation acetylene, methylacetylene,propadiene, butadiene or combinations thereof. As used herein, a highlyunsaturated hydrocarbon is defined as a hydrocarbon containing a triplebond, two conjugated carbon-carbon double bonds, or two cumulativecarbon-carbon double bonds. As used herein, an unsaturated hydrocarbonis defined as a hydrocarbon containing an isolated carbon-carbon doublebond. FIG. 1 illustrates an embodiment of a hydrogenation process thatutilizes a selective hydrogenation catalyst of the type disclosedherein. The hydrogenation process includes feeding an unsaturatedhydrocarbon stream 10 and a hydrogen (H₂) stream 20 to a hydrogenationreactor 30 within which the selective hydrogenation catalyst isdisposed. The unsaturated hydrocarbon stream 10 primarily comprises oneor more unsaturated hydrocarbons, but it can also contain one or morehighly unsaturated hydrocarbons such as for example and withoutlimitation acetylene, methylacetylene, propadiene, and butadiene.Alternatively, unsaturated hydrocarbon stream 10 and hydrogen stream 20can be combined in a single stream that is fed to hydrogenation reactor30.

In an embodiment, reactor 30 is a selective hydrogenation reactor thatcan belong to an acetylene removal unit of an unsaturated hydrocarbonproduction plant in a backend configuration. As used herein, “backend”refers to the location of the acetylene removal unit in an unsaturatedhydrocarbon production unit that receives the lower boiling fractionfrom a deethanizer fractionation tower that receives the higher boilingfraction from a demethanizer fractionation tower which receives a feedfrom an unsaturated hydrocarbon production process.

In an embodiment, reactor 30 is a selective hydrogenation reactor thatcan belong to an acetylene removal unit of an unsaturated hydrocarbonproduction plant in a frontend deethanizer configuration. As usedherein, “frontend deethanizer” refers to the location of the acetyleneremoval unit in an unsaturated hydrocarbon production unit that receivesthe lower boiling fraction from a deethanizer fractionation tower thatreceives a feed from an unsaturated hydrocarbon production process.

In an embodiment, reactor 30 is a selective hydrogenation reactor thatmay belong to an acetylene removal unit of an unsaturated hydrocarbonproduction plant in a frontend depropanizer configuration. As usedherein, “frontend depropanizer” refers to the location of the acetyleneremoval unit in an unsaturated hydrocarbon production unit that receivesthe lower boiling fraction from a depropanizer fractionation tower thatreceives a feed from an unsaturated hydrocarbon production process.

In an embodiment, reactor 30 is a selective hydrogenation reactor thatcan belong to an acetylene removal unit of an unsaturated hydrocarbonproduction plant in a raw gas configuration. As used herein, “raw gas”refers to the location of the acetylene removal unit in an unsaturatedhydrocarbon production unit that receives a feed from an unsaturatedhydrocarbon production process without any intervening hydrocarbonfractionation.

It is understood that hydrogenation reactor 30, and likewise theselective hydrogenation catalysts disclosed herein, are not limited touse in backend acetylene removal units, frontend deethanizer units,frontend depropanizer, or raw gas units and can be used in any processwherein a highly unsaturated hydrocarbons contained within anunsaturated hydrocarbon stream is selectively hydrogenated to aunsaturated hydrocarbon. In frontend deethanizer units, frontenddepropanizer, or raw gas units, the unsaturated hydrocarbon stream 10contains sufficient quantities of hydrogen for the hydrogenationreaction, and a hydrogen stream 20 may become unnecessary for thereaction.

In those embodiments wherein the acetylene removal unit is in a backendconfiguration, the highly unsaturated hydrocarbon being fed to thehydrogenation reactor 30 comprises acetylene. The mole ratio of thehydrogen to the acetylene being fed to hydrogenation reactor 30 can bein the range of from about 0.1 to about 10, alternatively from about 0.2to about 5, alternatively from about 0.5 to about 4.

In those embodiments wherein the acetylene removal unit is in a frontend deethanizer, front-end depropanizer or raw gas configuration, thehighly unsaturated hydrocarbon being fed to the hydrogenation reactor 30comprises acetylene. In such an embodiment, the mole ratio of thehydrogen to the acetylene being fed to the hydrogenation reactor 30 canbe in the range of from about 10 to about 3000, alternatively from about10 to about 2000, alternatively from about 10 to about 1500.

In those embodiments wherein the acetylene removal unit is in afront-end depropanizer or raw gas configuration, the highly unsaturatedhydrocarbon being fed to the hydrogenation reactor 30 comprisesmethylacetylene. In such an embodiment, the mole ratio of the hydrogento the methylacetylene being fed to the hydrogenation reactor 30 can bein the range of from about 3 to about 3000, alternatively from about 5to about 2000, alternatively from about 10 to about 1500.

In those embodiments wherein the acetylene removal unit is in afront-end depropanizer or raw gas configuration, the highly unsaturatedhydrocarbon being fed to the hydrogenation reactor 30 comprisespropadiene. In such an embodiment, the mole ratio of the hydrogen to thepropadiene being fed to the hydrogenation reactor 30 can be in the rangeof from about 3 to about 3000, alternatively from about 5 to about 2000,alternatively from about 10 to about 1500.

In another embodiment, reactor 30 can represent a plurality of reactors.The plurality of reactors can optionally be separated by a means toremove heat produced by the reaction. The plurality of reactors canoptionally be separated by a means to control inlet and effluent flowsfrom reactors or heat removal means allowing for individual oralternatively groups of reactors within the plurality of reactors to beregenerated. The selective hydrogenation catalyst can be arranged in anysuitable configuration within hydrogenation reactor 30, such as a fixedcatalyst bed. Carbon monoxide can also be fed to reactor 30 via aseparate stream (not shown), or it can be combined with hydrogen stream20. In an embodiment, the amount of carbon monoxide being fed to reactor30 during the hydrogenation process is less than about 0.15 mole percent(mol. %) based on the total moles of fluid being fed to reactor 30.

Hydrogenation reactor 30 can be operated at conditions effective toselectively hydrogenate highly unsaturated hydrocarbons to one or moreunsaturated hydrocarbons upon contacting the selective hydrogenationcatalyst in the presence of the hydrogen. The conditions are desirablyeffective to maximize hydrogenation of highly unsaturated hydrocarbonsto unsaturated hydrocarbons and to minimize hydrogenation of highlyunsaturated hydrocarbons to saturated hydrocarbons. In some embodiments,acetylene can be selectively hydrogenated to ethylene. Alternativelymethylacetylene can be selectively hydrogenated to propylene;alternatively propadiene can be selectively hydrogenated to propylene.Alternatively, butadiene can be selectively hydrogenated to butenes. Insome embodiments, the temperature within the hydrogenation zone can bein the range of from about 5° C. to about 300° C., alternatively fromabout 10° C. to about 250° C., alternatively from about 15° C. to about200° C. In some embodiments, the pressure within the hydrogenation zonecan be in the range of from about 15 (204 kPa) to about 2,000 (13,890kPa) pounds per square inch gauge (psig), alternatively from about 50psig (446 kPa) to about 1,500 psig (10,443 kPa), alternatively fromabout 100 psig (790 kPa) to about 1,000 psig (6,996 kPa).

Referring back to FIG. 1, an effluent stream 40 comprising unsaturatedhydrocarbons, including the one or more monoolefins produced inhydrogenation reactor 30, and any unconverted reactants exithydrogenation reactor 30. In an embodiment where hydrogenation reactor30 is in a backend acetylene removal unit configuration, effluent stream40 primarily comprises ethylene comprises less than about 5 ppm,alternatively less than about 1 ppm of highly unsaturated hydrocarbons.In embodiments wherein hydrogenation reactor 30 is in a frontenddeethanizer, frontend depropanizer, or raw gas acetylene removal unitconfiguration, effluent stream 40 primarily comprises ethylene comprisesless than about 5 ppm, alternatively less than about 1 ppm of acetylene,while other highly unsaturated hydrocarbons such as methylacetylene orpropadiene comprises less than about 5000 ppm, alternatively less thanabout 4000 ppm.

In an embodiment, a selective hydrogenation catalyst of the typedescribed herein can have a comparable catalytic activity when comparedto an otherwise similar catalyst lacking a catalyst support of the typedescribed herein. For example, a selective hydrogenation catalyst ofthis disclosure can have at least one performance property that isimproved when compared to an otherwise similar catalyst. In anembodiment, a selective hydrogenation catalyst of this disclosure has anoptimal balance of desirable properties. For example, a selectivehydrogenation catalyst of the type disclosed herein has a catalyticactivity or clean up temperature comparable to an otherwise similarcatalyst. The comparable catalytic activity can translate to acomparable clean up temperature. Hereinafter, an otherwise similarcatalyst refers to a selective hydrogenation catalyst comprising aninorganic catalyst support, palladium and one or more selectivityenhancers but lack a catalyst support of the type disclosed herein.Herein, the cleanup temperature is referred to as T1 and refers to thetemperature at which the acetylene concentration drops below 20 ppm inthe effluent when processing a representative frontend deethanizer,frontend depropanizer, or raw gas acetylene removal unit feed streamcomprising unsaturated hydrocarbon and highly unsaturated hydrocarbonssuch as acetylenes and diolefins. Determinations of T1 are described inmore detail for example in U.S. Pat. Nos. 7,417,007 and 6,417,136, eachof which are incorporated herein in their entirety. In an embodiment, aselective hydrogenation catalyst of the type disclosed herein can have aT1 of from about 80° F. to about 160° F., alternatively from about 85°F. to about 150° F., alternatively from about 90° F. to about 140° F.for fresh catalyst. In an embodiment, a selective hydrogenation catalystof the type described herein can display a selectivity window that isincreased when compared to an otherwise similar catalyst lacking acatalyst support of the type described herein. Herein, a selectivitywindow refers to the reaction time period over which the catalystdisplays a desired selectivity for a specified reaction. For example, aselective hydrogenation catalyst of the type disclosed herein whenemployed as a catalyst in acetylene hydrogenation reactors can display aselectivity window for ethylene of equal to or greater than about 200hours, alternatively equal to or greater than about 250 hours, oralternatively equal to or greater than about 300 hours. The selectivitywindow of selective hydrogenation catalysts of the type disclosed hereincan be increased by equal to or greater than about 50%, alternativelyequal to or greater than about 75%, or alternatively equal to or greaterthan about 100% when compared to an otherwise similar catalyst lacking acatalyst support of the type disclosed herein. Alternatively, theselectivity window of selective hydrogenation catalysts of the typedisclosed herein can be increased by equal to or greater than about 50%,alternatively equal to or greater than about 75%, or alternatively equalto or greater than about 100% when compared to an otherwise identicalcatalyst lacking a catalyst support of the type disclosed herein.

In an embodiment, a selective hydrogenation catalyst of the typedisclosed herein can have an operating window of from about 35° F. toabout 120° F., alternatively from about 40° F. to about 80° F., oralternatively from about 45° F. to about 60° F. The operating window ofa selective hydrogenation catalyst of the type described herein can beincreased by greater than about 10%, alternatively greater than about15%, alternatively greater than about 20% when compared to an otherwisesimilar catalyst prepared in the absence of catalyst support of the typedescribed herein. Alternatively, the operating window of a selectivehydrogenation catalyst of the type described herein can be increased bygreater than about 10%, alternatively greater than about 15%,alternatively greater than about 20% when compared to an otherwiseidentical catalyst prepared in the absence of catalyst support of thetype described herein. An operating window (ΔT) is defined as thedifference between a runaway temperature (T2) at which 3 wt. % ofethylene is hydrogenated from a feedstock comprising highly unsaturatedand unsaturated hydrocarbons, and the cleanup temperature (T1). ΔT is aconvenient measure of the catalysts selectivity window and operationstability in the hydrogenation of highly unsaturated hydrocarbons (e.g.,acetylene) to unsaturated hydrocarbons (e.g., ethylene). The moreselective a catalyst, the higher the temperature beyond T1 required tohydrogenate a given unsaturated hydrocarbons (e.g., ethylene). The T2 iscoincident with the temperature at which a high probability of runawayethylene hydrogenation reaction could exist in an adiabatic reactor.Therefore, a larger ΔT translates to a more selective catalyst and awider operation window for the complete acetylene hydrogenation.

In an embodiment a method comprises providing a catalyst support of thetype disclosed herein and utilizing the catalyst support to form aselective hydrogenation catalyst. The selective hydrogenation catalystcan be further processed into a packaged product containing orassociated with written material. In some embodiments, the writtenmaterial can provide information on the selectivity window of aselective hydrogenation catalyst formed from a catalyst support of thetype disclosed herein alone or in comparison to a selectivehydrogenation catalyst prepared in the absence of a catalyst support ofthe type disclosed herein. In some embodiments, the written material canprovide instructions and/or recommendations for utilization of theselective hydrogenation catalyst in one or more applications. Forexample, the written material can indicate the selective hydrogenationcatalyst formed from a catalyst support of the type disclosed herein(e.g., having a bimodal distribution of pore diameters) is suitable foruse in applications where a broader selectivity window is desirable.

EXAMPLES

The disclosure having been generally described, the following examplesare given as particular embodiments of the disclosure and to demonstratethe practice and advantages thereof. It is understood that the examplesare given by way of illustration and are not intended to limit thespecification of the claims to follow in any manner.

Example 1

This example illustrates the preparation of various palladium-containingcatalyst compositions to be used in a hydrogenation process. Catalysts Athru E were prepared as follows: The α-alumina support having a surfacearea ranging from 5 m²/g to 12 m²/g was supplied by BASF. The supportwas then chloride-treated, followed by the addition of palladium andsilver as described herein. Tables 1, 2, and 3 summarize the physicalproperties of catalysts A thru E. FIGS. 2-6 show the pore sizedistribution from mercury pore symmetry for catalysts A thru E. Thedashed lines represent the sample distributions while the solid linerepresents percentage cumulative intrusion.

TABLE 1 Pd Ag Surface Area Catalyst Form (ppm) (ppm) (m²/g)¹ A pellet252 1718 9.57 B extrudate 284 2492 8.12 C extrudate 308 1869 8.57 Dpellet 267 1840 6.71 E extrudate 307 1889 11.22 Pellets were ~4 mm × 4mm extrudates were ~5 mm × 3 mm ¹By Brunauer, Emmett, and Teller method

TABLE 2 RANGE 1 RANGE 2 RANGE 3 RANGE 4 Pore size % Pore size % Poresize % Pore size % Diameter total Diameter total Diameter total Diametertotal Cat- range pore range pore range pore range pore alyst (nm) volume(nm) volume (nm) volume (nm) volume A 29736 to 2000 0.51 — — 2000 to 4594.29 45 to 10 5.2 B 21409 to 2,000 0.15 2000 to 332 19.32 332 to 3580.53 — — C 21449 to 230 24.7 — — 230 to 30 74.56 30 to 10 0.74 D 21464to 280 23.9 — — 280 to 30 76.1 — — E 21469 to 280 17.53 — — 280 to 3676.87 36 to 10 5.6

TABLE 3 Surface Area Pore volume Catalyst Form (m²/g)¹ (cc/g)² A pellet9.57 0.326 B extrudate 8.12 0.344 C extrudate 8.57 0.253 D pellet 6.710.212 E extrudate 11.22 0.265 ¹By Brunauer, Emmett, and Teller method²By ASTM UOP578-02

Example 2

Catalyst performance runs were made as follows: About 20 mL of catalystwas mixed with 40 mL of alundum and placed in a stainless steel jacketedreactor tube having a 0.692 inch inner diameter and a length of about 18inches. The catalyst resided in the middle of the reactor and both endsof the reactor were packed with about 10 mL of alundum. The reactiontemperature was controlled by circulating ethylene glycol through thejacket of the reactor tube. The catalyst was then activated withhydrogen at a flowrate of 200 mL/min at atmospheric pressure at thelisted temperature for two hours. The catalyst was then contacted withthe feed gas (approximately: 13 wt. % methane, 85.8 wt. % ethylene, 1.2wt. % acetylene, and 0.1 wt. % hydrogen) at about 913 mL/min at 200psig. Some runs used a higher hydrogen concentration and are notedlikewise. The reaction temperature was adjusted to yield an acetyleneconversion of about 90%. Conversion is referred to as the disappearanceof acetylene. Gas analysis was performed by gas chromatography using aKCl-Al₂O₃ PLOT column. FIG. 7 shows the temperature needed to maintain a90% conversion of acetylene as a function of time. FIG. 8 shows theselectivity to ethylene as a function of time.

The selectivity (sel.) to ethylene was also calculated using thefollowing set of equations, where “C₄” represents butane, butenes andbutadiene and where “heavies” refer to hydrocarbons having more carbonatoms than C₄:

selectivity to ethane=(weight of ethane made/weight of acetyleneconsumed)*100

selectivity to C₄'s=(weight of C₄'s made/weight of acetyleneconsumed)*100

selectivity to heavies=(weight of heavies made/weight of acetyleneconsumed)*100

selectivity to ethylene=100−sel. to ethane−sel. to C₄'s−sel. to heavies

The results demonstrate that while all the catalysts displayed goodactivity as indicated by the comparable temperatures at time zero,catalysts of the type disclosed herein (i.e., catalysts C, D, and E)displayed a leveling of the adjusted temperature, FIG. 7. This incontrast to catalysts A and B which do not have a catalyst support witha pore distribution of the type disclosed herein. In the case ofcatalysts A and B, the temperature begins to increase toward the end ofthe run. Further, referring to FIG. 8, with regards to selectivitycatalysts C, D, and E displayed an increased selectivity as indicated bya plateau in selectivity over the time period investigated. In contrast,catalysts A and B show a decline in selectivity after about 150 hours.Catalysts C, D, and E are selective hydrogenation catalysts having apore size distribution, specifically the presence of the peak around1,000 nm in the pore size distribution while catalysts A and B do nothave this peak.

Additional Embodiments

The following enumerated embodiments are provided as non-limitingexamples:

-   1. A composition comprising:    -   an extruded inorganic support comprising an oxide of a metal or        metalloid; and    -   at least one catalytically active metal,    -   wherein the extruded inorganic support has pores, a total pore        volume, and a pore size distribution; wherein the pore size        distribution displays at least two peaks of pore diameters, each        peak having a maximum; wherein a first peak has a first maximum        of pore diameters of equal to or greater than about 120 nm and a        second peak has a second maximum of pore diameters of less than        about 120 nm; and wherein greater than or equal to about 5% of a        total pore volume of the extruded inorganic support is contained        within the first peak of pore diameters.-   2. The composition of embodiment 1 wherein the first maximum of the    first peak of pore diameters is from about 200 nm to about 9000 nm.-   3. The composition of embodiment 1 or 2 wherein greater than or    equal to about 10% of the total pore volume of the extruded    inorganic support is contained within the first peak of pore    diameters.-   4. The composition of embodiment 1 or 3 wherein the first maximum of    the first peak of pore diameters is from about 400 nm to about 8000    nm.-   5. The composition of embodiment 4 wherein greater than or equal to    about 15% of the total pore volume of the extruded inorganic support    is contained within the first peak of pore diameters.-   6. The composition of any preceding embodiment wherein the oxide of    a metal or metalloid consists essentially of silica, titania,    alumina, or aluminate.-   7. The composition of embodiment 1, 2, 3, 4, or 5 wherein the oxide    of a metal or metalloid consists essentially of a spinel.-   8. The composition of any preceding embodiment having a surface area    of from about 1 m2/g to about 35 m²/g.-   9. The composition of any preceding embodiment having a total pore    volume of from about 0.1 cc/g to about 0.6 cc/g as determined by    differential mercury intrusion.-   10. The composition of any preceding embodiment wherein the distance    between the first maximum of the first peak and the second maximum    of the second peak is at least about 400 nm.-   11. The composition of any preceding embodiment wherein the first    peak is non-Gaussian and has a peak width at half height that is    greater than the peak width at half height of the second peak.-   12. The composition of any preceding embodiment further comprising a    halide.-   13. The composition of any preceding embodiment further comprising a    Group 10 metal.-   14. The composition of any preceding embodiment further comprising a    Group 1B metal.-   15. The composition of any preceding embodiment further comprising    chloride.-   16. A method of preparing a hydrogenation catalyst comprising:    -   extruding a mixture comprising an oxide of a metal or metalloid,        a pore former, and water to form an extrudate;    -   drying the extrudate to form a dried extrudate;    -   calcining the dried extrudate to from a calcined extrudate;    -   contacting the calcined extrudate with a chlorine-containing        compound to form a chlorided support;    -   reducing the amount of chloride in the chlorided support to form        a cleaned chlorided support; and    -   contacting the cleaned chlorided support with a Group 10 metal        and a Group 1B metal to form a hydrogenation catalyst,    -   wherein a pore size distribution for the hydrogenation catalyst        displays at least two peaks of pore diameters, each peak having        a maximum, and wherein a first peak has a first maximum of pore        diameters that is equal to or greater than about 120 nm and a        second peak has a second maximum of pore diameters that is less        than about 120 nm.-   17. The method of embodiment 16 wherein the calcined extrudate, the    chlorided support, the cleaned chlorided support, or the    hydrogenation catalyst has a surface area of from about 1 m²/g to    about 35 m²/g.-   18. The method of embodiment 16 or 17 wherein the calcined    extrudate, the chlorided support, the washed chlorided support, or    the hydrogenation catalyst has a total pore volume of from about 0.1    cc/g to about 0.6 cc/g as determined by differential mercury    intrusion.-   19. The method of embodiment 16, 17, or 18 wherein the extrudate    consists essentially of silica, titania, alumina, or aluminate.-   20. The method of embodiment 16, 17, or 18 wherein the extrudate    consists essentially of alpha alumina.-   21. The method of embodiment 16, 17, 18, 19, or 20 wherein greater    than or equal to 5% of a total pore volume of the hydrogenation    catalyst is contained within the first peak of pore diameters.-   22. An extruded inorganic support comprising an oxide of a metal or    metalloid, wherein a pore size distribution for the extruded    inorganic support displays at least two peaks of pore diameters,    each peak having a maximum; wherein a first peak has a first maximum    of pore diameters of equal to or greater than about 120 nm and a    second peak has a second maximum of pore diameters of less than    about 120 nm; wherein greater than or equal to 15% of a total pore    volume of the extruded inorganic support is contained within the    first peak of pore diameters; and wherein the inorganic support has    a surface area of from about 5 m²/g to about 15 m²/g.-   23. A method of preparing a hydrogenation catalyst comprising:    -   selecting an inorganic support having a multimodal distribution        of pore diameters, wherein at least one distribution of pore        diameters comprises pores having a diameter of equal to or        greater than about 120 nm;    -   extruding a mixture comprising the inorganic support and water        to form an extrudate; drying the extrudate to form a dried        extrudate;    -   calcining the dried extrudate to from a calcined extrudate; and    -   contacting the calcined extrudate with a Group VIII metal and a        Group 1B metal to form a hydrogenation catalyst.-   24. The method of embodiment 23 further comprising contacting the    calcined extrudate with a chlorine-containing compound to form a    chlorided support; contacting the chlorided support with a wash    solution to form a washed chlorided support; contacting the washed    chlorided support with the Group VIII metal and the Group 1B metal    to form the hydrogenation catalyst.-   25. A method for selectively hydrogenating a highly unsaturated    hydrocarbon to a less unsaturated hydrocarbon in an olefin rich    hydrocarbon stream comprising introducing into a reactor a    hydrocarbon fluid stream comprising a highly unsaturated hydrocarbon    in the presence of hydrogen and a catalyst composition under    conditions effective to convert the highly unsaturated hydrocarbon    to a less unsaturated hydrocarbon, wherein at least 50% of the    catalyst composition comprises the hydrogenation catalyst produced    according to embodiment 23.-   26. A method comprising:    -   preparing a plurality of extruded inorganic supports consisting        essentially of silica, titania, alumina, or a spinel;    -   plotting the pore diameter as a function of a log of        differential mercury intrusion for the extruded inorganic        support; and    -   identifying the extruded inorganic supports having at least two        peaks, each peak having a maximum, wherein a first peak        comprises pores with a first pore diameter maximum equal to or        greater than about 120 nm, and wherein the first peak of pore        diameters represents greater than or equal to about 5% of a        total pore volume of the extruded inorganic support.-   27. The method of embodiment 26 further comprising marketing the    extruded inorganic supports for use in preparing a selective    hydrogenation catalyst.-   28. A hydrogenation catalyst comprising a Group 10 metal, a Group 1B    metal and at least one of the identified extruded inorganic supports    of any preceding embodiment.-   29. A packaged product comprising least one of the identified    extruded inorganic supports of any preceding embodiment and written    material describing use of the identified extruded inorganic    supports in the preparation of hydrogenation catalysts having a    reduced fouling rate.

While embodiments of the invention have been shown and described,modifications thereof can be made by one skilled in the art withoutdeparting from the spirit and teachings of the invention. Theembodiments described herein are exemplary only, and are not intended tobe limiting. Many variations and modifications of the inventiondisclosed herein are possible and are within the scope of the invention.Where numerical ranges or limitations are expressly stated, such expressranges or limitations should be understood to include iterative rangesor limitations of like magnitude falling within the expressly statedranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4,etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.). Use of theterm “optionally” with respect to any element of a claim is intended tomean that the subject element is required, or alternatively, is notrequired. Both alternatives are intended to be within the scope of theclaim. Use of broader terms such as comprises, includes, having, etc.should be understood to provide support for narrower terms such asconsisting of, consisting essentially of, comprised substantially of,etc.

Accordingly, the scope of protection is not limited by the descriptionset out above but is only limited by the claims which follow, that scopeincluding all equivalents of the subject matter of the claims. Each andevery claim is incorporated into the specification as an embodiment ofthe present invention. Thus, the claims are a further description andare an addition to the embodiments of the present invention. Thedisclosures of all patents, patent applications, and publications citedherein are hereby incorporated by reference, to the extent that theyprovide exemplary, procedural or other details supplementary to thoseset forth herein.

What is claimed is:
 1. A composition comprising: an inorganic supportcomprising an oxide of a metal or metalloid; a halide; and at least onecatalytically active metal, wherein the inorganic support has pores, atotal pore volume, and a pore size distribution; wherein the pore sizedistribution displays at least two peaks of pore diameters, each peakhaving a maximum; wherein a first peak has a first maximum of porediameters of from greater than 1,000 nm to about 6,000 nm; wherein asecond peak has a second maximum of pore diameters of less than about120 nm; and wherein greater than or equal to about 15% of the total porevolume of the inorganic support is contained within the first peak ofpore diameters; and wherein the inorganic support is a sphere.
 2. Thecomposition of claim 1, wherein the inorganic support is an extrudedinorganic support.
 3. The composition of claim 1, wherein the inorganicsupport is an agglomerated inorganic support.
 4. The composition ofclaim 1, wherein the oxide of a metal or metalloid consists essentiallyof silica, titania, alumina, or aluminate.
 5. The composition of claim1, wherein the oxide of a metal or metalloid consists essentially of aspinel.
 6. The composition of claim 1, having a total pore volume offrom about 0.1 cc/g to about 0.6 cc/g as determined by differentialmercury intrusion.
 7. The composition of claim 1, wherein the first peakis non-Gaussian and has a peak width at half height that is greater thanthe peak width at half height of the second peak.
 8. The composition ofclaim 1, further comprising a Group 10 metal and a Group 1B metal. 9.The composition of claim 1, wherein the Group 10 metal comprisespalladium and the Group 1B metal comprises silver.
 10. The compositionof claim 1, wherein the halide is chloride.
 11. The composition of claim1, wherein the at least one catalytically active metal comprisespalladium and silver; the halide comprises chloride; and the oxide of ametal or metalloid comprises α-alumina.
 12. The composition of claim 1,wherein the at least one catalytically active metal comprises palladiumand the palladium is present in the composition in an amount of fromabout 0.005 wt. % to about 2 wt. % based on the total weight of thecomposition.
 13. The composition of claim 12 wherein greater than about90 wt. % of the palladium is concentrated near the periphery of thecomposition.
 14. The composition of claim 1, wherein the inorganicsupport has a surface area of from about 3 m²/g to about 27 m²/g. 15.The composition of claim 1 wherein the inorganic support is an oil dropshaped inorganic support.
 16. A composition comprising: a support formedfrom a high surface area alumina having a spherical shape; and at leastone catalytically active metal, wherein the support has pores, a totalpore volume, and a pore size distribution; wherein the pore sizedistribution displays at least two peaks of pore diameters, each peakhaving a maximum; wherein a first peak has a first maximum of porediameters of equal to or greater than 1,000 nm to about 6,000 nm;wherein a second peak has a second maximum of pore diameters of lessthan about 120 nm; and wherein greater than or equal to about 15% of thetotal pore volume of the support is contained within the first peak ofpore diameters.
 17. The composition of claim 16 wherein the support isagglomerated.
 18. The composition of claim 16 wherein the support is anoil drop shaped support.
 19. The composition of claim 16 wherein thesupport is an extrudate.
 20. The composition of claim 16 having asurface area of from about 1 m²/g to about 35 m²/g.
 21. The compositionof claim 16 having a total pore volume of from about 0.1 cc/g to about0.9 cc/g as determined by differential mercury intrusion.
 22. Thecomposition of claim 16 wherein the distance between the first maximumof the first peak and the second maximum of the second peak is at leastabout 400 nm.
 23. The composition of claim 16 wherein the first peak isnon-Gaussian and has a peak width at half height that is greater thanthe peak width at half height of the second peak.
 24. The composition ofclaim 16 further comprising a halide, a Group 10 metal, and a Group 1Bmetal.
 25. A method of preparing a hydrogenation catalyst comprising:shaping a mixture comprising a high surface area alumina, a pore former,and water to form a shaped support, wherein the shaped support comprisesa sphere; drying the shaped support to form a dried support; calciningthe dried support to from a calcined support; contacting the calcinedsupport with a chlorine-containing compound to form a chlorided support;reducing the amount of chloride in the chlorided support to form acleaned support; and contacting the cleaned support with a Group 10metal and a Group 1B metal to form a hydrogenation catalyst, wherein apore size distribution for the hydrogenation catalyst displays at leasttwo peaks of pore diameters, each peak having a maximum, wherein a firstpeak has a first maximum of pore diameters that is equal to or greaterthan 1,000 to about 6,000 nm, wherein a second peak has a second maximumof pore diameters that is less than about 120 nm, and wherein greaterthan or equal to about 15% of a total pore volume of the hydrogenationcatalyst is contained within the first peak of pore diameters.
 26. Themethod of claim 25, wherein the hydrogenation catalyst has a total porevolume of from about 0.1 cc/g to about 0.6 cc/g as determined bydifferential mercury intrusion.
 27. The method of claim 25, wherein thehydrogenation catalyst has a surface area of from about 3 m²/g to about27 m²/g.
 28. A spherical particle shape support formed from a highsurface area alumina, wherein a pore size distribution for the sphericalparticle shape support displays at least two peaks of pore diameters,each peak having a maximum; wherein a first peak has a first maximum ofpore diameters of equal to or greater than 1,000 nm to about 6,000 nm,wherein a second peak has a second maximum of pore diameters of lessthan about 120 nm; wherein greater than or equal to about 15% of a totalpore volume of the spherical particle shape support is contained withinthe first peak of pore diameters; and wherein the spherical particleshape support is a sphere or an extrudate.
 29. A method for selectivelyhydrogenating a highly unsaturated hydrocarbon to a less unsaturatedhydrocarbon in an olefin rich hydrocarbon stream comprising introducinginto a reactor a hydrocarbon fluid stream comprising a highlyunsaturated hydrocarbon in the presence of hydrogen and a catalystcomposition under conditions effective to convert the highly unsaturatedhydrocarbon to a less unsaturated hydrocarbon, wherein at least 50% ofthe catalyst composition comprises the hydrogenation catalyst producedaccording to claim 25.